TTC, Living with MIL and 5yo only wants to sleep with me & hubby

Sab

Help?! My husband, myself and our 5 year old are currently living with my mother in law as we prepare to become homeowners. Bedrooms are limited and our 5 only want to sleep with us and not with my mother in law even tho she graciously offers to keep him ( she knows we are TTC). Any tips on how to get it in during my fertile window??? We’ve been TTC for a year! HELP!